try to practice yoga, specially pranayama & meditation.Meditation has the scientific basis to improve our brain's capacity.Again, we have two types of memory, long term memory & short term memory.You can compare these two, long term with computer hard disk & short term with RAM.The more you repeat a new stuff, it will go to the long term memory stage.When we first encounter with a new learning, it first goes to the short term memory section. Repetition in appropriate interval makes it to transfer itself to long term memory.
As for sleeping time, this vary from person to person.Whenever 8 hours is standard, you often find some people who live with just 3 hours of sleep.Sleeping time decreases with increasing age.A 1 month old child sleeps for almost 20 hours whereas for a 70 years old person 4 hours is enough.

I read somewhere that every event in one's life is stored for a whole life span, just the neural pathways connecting those events to our conscious mind don't get used as much, and thus become dormant.
This, to me, is a much more cohesive explanation for random occurrences of people just remembering long-forgotten things and details. The only thing needed to make those neural pathways work again is to get a trigger which just sends a barrage of neural pulses to that particular area of the brain. Like seeing a dog on the street might suddenly, impulsively almost, remind you of the dog you had when you were a kid who had died years ago.
Sleep does effect memory formation, but not just any kind of sleep. What the brain really needs is REM sleep. That's when our brains go into dream mode, research has shown that during REM sleep, there are massive neural 'surges' of energy, which really cannot properly be explained, but which seems to have a very calming and refreshing effect on the brain, making it ready to take in new information and process it with the stuff already in there.\
For most adults, 4-7 hours is plenty of sleep to get through most days. We do tend to make up for lost sleeping hours during the weekends though, consciously or not.

To keep things in memory for a long time, we should put them in our mind with a clear cognition about them, something like description and definition. We can also relate them to some of our familiar things or places. But of course, we cannot remember ALL the things, so get out of your mind the stuffs that are not necessary. By this way, your brain will help you store which is most important to you effectively.
In business, remembering other people's name is very important, especially in the service industry where you usually work with clients. How to remember all when there are many people around you that sometimes you unnoticeable forgot their name? One way is to relate their name to their appearance. I realized that there are many cases that one's name suits perfectly to his characteristics or out-site look. Another one is to keep a list of their name on your phone and add some details. It will be easily to discover their names on your own when you definitely forgot their names.